1. Field of the Invention
The present invention relates to a room-temperature curable organopolysiloxane composition that generates a cured product or coating film with good transparency and good strength, and in particular relates to a room-temperature curable organopolysiloxane composition that is ideal for use as a coating material for electrical or electronic components or circuits, a sealant for liquid crystal display elements, and a paint that generates an antifouling coating, which is applied to underwater structures to prevent the adhesion and growth of aquatic organisms on the surface of such structures. In this specification, “underwater structures” means ships, port installations, buoys, pipelines, bridges, undersea bases, seabed oil field excavation equipment, water supply pipes for power generation stations, nets for aquatic farming, and fixed nets and the like.
2. Description of the Prior Art
Conventionally, many room-temperature curable silicone rubber compositions which generate rubber like elastic bodies at room temperature are already known. Cured rubbers obtained from room-temperature curable silicone rubber compositions (hereafter referred to as “RTV”) display superior weather resistance, durability, heat resistance and cold resistance when compared with other organic-based rubbers, and are consequently used in a variety of fields, particularly within the field of construction, where they are used for a variety of applications including as adhesives for bonding glass together, adhesives between metals and glass, and as sealants between masonry joints. Furthermore, because of their adhesion to adherends such as epoxy resins, alcohol-elimination type RTVs tend to be widely used for bonding and coating electrical or electronic components. In recent years, alcohol-elimination type RTVs have also been widely applied as sealants for liquid crystal display elements, which are being produced in rapidly increasing numbers.
Conventional RTVs have basically satisfied performance requirements for factors such as insulation and dust prevention of electrical or electronic components or circuits. However, with recent moves to even more finely detailed circuit design, RTV coating films with greater strength are now being sought. A material capable of adequately meeting these requirements, which requires no solvent, and generates a cured product or coating with good transparency and superior strength has not been available.
On the other hand, in recent years, RTVs have become widely used as coatings for building structures, production plants, the internal surfaces of water pipes, and the external surfaces of water pipes and the like. Furthermore, countermeasures for preventing the adhesion and growth of aquatic organisms on underwater structures have involved the application of an antifouling paint containing a toxic antifouling agent such as an organotin compound or cuprous oxide to the structure. However, although such measures substantially prevented the adhesion and growth of any aquatic organisms, because a toxic antifouling agent was used, the environmental, safety, and hygiene conditions during production and application of the paint were undesirable, and furthermore when placed in the water, the toxic antifouling agent was gradually eluted from the paint film, meaning that when viewed over an extended period, there was a danger of polluting the water environment, and as a result the use of such antifouling paints has now been banned by law.
In contrast, non-toxic antifouling paints that exhibit antifouling properties by lowering the surface tension of the paint film have been proposed as paints that can prevent the adhesion and growth of aquatic organisms, and yet contain no toxic antifouling agents. For example, the combining of liquid paraffin, petrolatum, or a mixture of liquid paraffin and petrolatum with a RTV has been proposed (Japanese Laid-open Patent publication (kokai) No. 58-13673 (JP58-13673A), Laid-open Patent publication (kokai) No. 62-84166(JP62-84166A)).
Furthermore, non-toxic antifouling paint compositions which utilize the volumetric shrinkage accompanying the curing of a reaction curing type silicone resin, so that a silicone resin containing an unreactive polar group and with poor compatibility bleeds out to the surface, thereby combining antifouling properties with the low surface tension of the reaction curing type silicone resin, have also been proposed. In other words, the use of resins in which a polar group selected from amongst amino groups, carboxyl groups, epoxy groups and polyoxyethylene groups with hydroxyl group terminals is bonded to a silicon atom via a bivalent aliphatic hydrocarbon group (Japanese Patent publication No. 2503986 (JP2503986B)), and the use of silicone resins with an alkoxy group introduced at a molecular terminal silicon atom via an ethylene oxide or propylene oxide group (Japanese Patent publication No. 2952375 (JP2952375B)) as the silicone resin containing an unreactive polar group have already been proposed. However, these resins were still unable to provide satisfactory performance in terms of the long term endurance of the antifouling properties.